1. Field of the Invention
The invention relates to determining dead space fraction of a subject based on blood gas measurements that are taken only intermittently.
2. Description of the Related Art
Systems configured to determine dead space fraction are known. Generally, dead space fraction refers to the ration between respiratory dead space and tidal volume. Respiratory dead space refers to the volume of each breath by a subject that does not participate in gas exchange with the blood of the subject. For example, this volume would include the airway of the subject outside of the lungs and any volume in the lungs of the subject which is ventilated but not perfused and therefore does not participate in gas exchange. The dead space fraction of a subject can be used for diagnosis, to tailor therapy to the subject's needs, and/or for other purposes
In order to determine dead space fraction in conventional systems, a blood gas measurement must be taken. This generally requires blood to be collected from a subject for each determination of dead space fraction. As such, dead space fraction is typically only updated intermittently (e.g., at intervals of about 24 hours while the patient is in intensive care).